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How to calculate rms voltage, rms current and frequency from real time data?

Hello,

 

I need to calculate the real time rms voltage, rms current and frequency of the received voltage and current graphs using visa read. Actually am trying to monitor the voltage and current parameters of AC load, in this case, am using a set of 4 light bulbs at the moment. Expected frequency is 50 Hz, and rms voltage close to 240v AC, current about 1A. 

 

Attached is the vi picture of what I have been able to achieve so far, courtesy of labview forums. But I need to finally finish this vi by calculating the Vrms, Irms and frequecy. The front panel shows the voltage (Chart V) and current (Chart I) after scaling. Chart VI represents ADC value 0 ~ 1023 of received data. Aray V & I show the binary bits received up to 10 bits of useful data from ADC. Each sine wave from ADC is sampled at 25 samples for the ADC conversion, and sampling frequency of 1.28kH.

 

I have tried using the RMS vi, but seems I don't know how to configure it correctly to get desired results. Also when I make changes like switching of one of the bulbs so that their is current change, I need to refresh the SERIAL port first before changes show up on the VI. Any ideas on how to improve on this are highly appreciated.

 

Otherwise, I would appreciate if somebody helps me MODIFY my VI to read the rms values and frequency from received data. This is the last piece of my project, I do appreciate all the help rendered. Am currently using labview labview 2014, student version!

 

Gavin.

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hello,

 

note that peak voltage (Vpeak) is (240 * 1.414) = 399 V and peak current about 1.414 if intended rms current is 1A.

 

Gavin.

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